I did some testing about his HP :
As max hunger wolfgang with c_supergodmode() and tentacles spikes (102 damage), using the Global Pause mod and ConsoleWorldEntityUnderMouse():Remove() to control any creepy crawler coming to him and remove his 'shield generators'.
First try removing every single crawler : he lasted 119 hits. 1 out of 119 was shielded. 118x102=12'036
Second third and fourth tries, letting 10 of them go to him (assuming it was a heal) : 157 hits took him down. 0 out of 157 shielded. 157x102 = 16'014.
Total : he seems to have 12'000 HP, crawlers seem to heal him for 400 HP each assuming this is a flat heal.
As far as phases go, i noticed he summons the first round of crawlers + shield when he loses 4'000 HP (he did it every single time the first spike hit 60%). Whether the other rounds are time based or HP based (i think the latter), idk yet.. got to stop procrastinating at some point.
edit : max hunger wolf not max hp